1. Field of the Invention
The present invention is related to an optical fiber processing apparatus for controlling transmission loss.
2. Description of Related Art
Generally, optical fiber is produced by stretching quartz glass based material when the material is in a melted state heated to a high-temperature of approximately 2000° C. After the stretched fiber core is rapidly cooled inside a cooling device such as a cooling cylinder or the like, the fiber core is coated, wrapped with a coating resin. It is known that during this series of steps, NBOHC (Non-Bridging Oxygen Hole Center Si—O) arises when the melted fiber core is rapidly cooled.
The NBOHC remaining in the optical fiber combines with hydrogen remaining in the optical fiber during the production process or hydrogen arising from the resinous coating the optical fiber, becoming Si—OH. If the hydroxyl (—OH) arises, optical loss in the 1.38 micrometer optical communication wavelength increases due to absorption loss from the hydroxyl, resulting in a deterioration in the transmission characteristics of the optical fiber.
The method of exposing the optical fiber to gas containing deuterium is known for use to improve the problem of deteriorating transmission characteristics. This well-known method involves reacting the NBOHC inside the quartz glass with deuterium (D2) and generating deuteroxyl (—OD) instead of hydroxyl (—OH). Because the optical absorption band of deuteroxy is 1.87 micrometers, wavelength region where absorption loss is substantial is shifted beyond the optical communication wavelength region of the 1.3 micrometer, thereby reducing transmission loss of the optical communication wavelength region. However, a problem affecting this well-known method is that the duration of exposure to the deuterium containing gas must continue for a day or a week, this substantial time requirement rendering the method inefficient.
Accordingly, a method in which a reactor chamber filled with gas containing deuterium is used as a decompression chamber in order to reduce time of exposure to the deuterium containing gas, while using a storage chamber that enables the valuable deuterium to be reused instead of being discarded has been proposed in Japanese Patent Application No. 2003-424632.
However, the above method which employs a decompression reactor and a storage chamber requires a plurality of pumps such as a pump in order to facilitate decompression in the reactor, a pump in order to supply the deuterium containing gas inside the storage chamber to the reactor after decompression is complete and a pump to return the deuterium containing gas to the storage chamber after that operation. Accordingly, the problem arises of considerable expense required for equipment costs.
Further, the storage chamber is a supply container for supplying the deuterium containing gas to the inside of the reactor and therefore there must be a one-to-one pairing relationship between the reactor and the storage chamber. This means that in order to process a plurality of optical fibers simultaneously, a plurality of reactors are required for setting the optical fiber which then requires the same number of storage chambers to be provided as the number of reactors. This requires usage of substantial space to install the equipment and engenders considerable expense for equipment costs.
Here, a method in which a single large storage chamber or a highly pressurized storage chamber is employed to correspond to a plurality of reactors is conceivable. However, increasing the size of the storage chamber raises costs, while in providing a high-pressure container, substantial back pressure arises from the vacuum pump and it is not possible to create a sufficient vacuum condition in the reactor.